In a conventional programmable logic controller, communication has been performed by regarding a plurality of networks as one network using a virtual IP address. As for programmable logic controllers connected to different networks having different IP network addresses, respectively, a routing function is installed in the programmable logic controllers to perform communication to the different networks.
Network devices of types different from the Ethernet® (“®” is hereinafter omitted) are connected to one another by using a heterogeneous network gateway.
Communication with a communication device connected to a network having a different network address from a real IP address can be performed by using, for example, a routing function disclosed in Patent Literature 2. However, for a programmable logic controller and a communication device connected to different types of networks, a heterogeneous network gateway system disclosed in Patent Literature 3 needs to be established.